An Updated History of : 2000-2020.

Since its inaugural issue nearly half a century ago, has served as a premier source for reports on scientific and clinical advances in the field of antimicrobial chemotherapy. As a follow-up to the previous "History of from 1972 to 1998" written by George A. Jacoby (Antimicrob Agents Chemother 43:999-1002, 1999, https://doi.

Ceftolozane-tazobactam and ceftazidime-avibactam activity against β-lactam-resistant Pseudomonas aeruginosa and extended-spectrum β-lactamase-producing Enterobacterales clinical isolates from U.S. medical centres.

Background: Despite availability of ceftolozane-tazobactam (C/T) and ceftazidime-avibactam (CZA) for several years, the individual spectrum of activity of each agent may not be widely known. We compared the activity of C/T and CZA against convenience samples of 119 extended-spectrum β-lactamase (ESBL)-producing Enterobacterales and 60 β-lactam-resistant Pseudomonas aeruginosa clinical isolates collected from three U.S.

Efficacy of Apramycin against Multidrug-Resistant Acinetobacter baumannii in the Murine Neutropenic Thigh Model.

Apramycin, an aminocyclitol aminoglycoside, was rapidly bactericidal against In a neutropenic murine thigh infection model, treatment-associated CFU reductions of >4 log per thigh were observed for all exposures for which area under the curve (AUC)/MIC ratio was >50 and maximum concentration of drug in serum ()/MIC was ≈10 or higher. Based on these findings, we suggest that apramycin deserves further preclinical exploration as a repurposed therapeutic for multidrug-resistant Gram-negative pathogens, including .

Invitro Apramycin Activity against multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa.

The in vitro activity of apramycin was compared to that of amikacin, gentamicin, and tobramycin against multidrug-resistant, extensively drug-resistant, and pandrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa. Apramycin demonstrated an MIC/MIC of 8/32μg/ml for A. baumannii and 16/32μg/ml for P.

Susceptibility of Multidrug-Resistant Gram-Negative Urine Isolates to Oral Antibiotics.

Increasing resistance among Gram-negative uropathogens limits treatment options, and susceptibility data for multidrug-resistant isolates are limited. We assessed the activity of five oral agents against 91 multidrug-resistant Gram-negative urine isolates that were collected from emergency department/hospitalized patients. Fosfomycin and nitrofurantoin were most active (>75% susceptibility).

Activity of fosfomycin and comparison of several susceptibility testing methods against contemporary urine isolates.

Fosfomycin is recommended as first-line treatment for acute uncomplicated cystitis in women. It has demonstrated in vitro activity against a variety of pathogens; however, a paucity of data are available from the USA. We determined the susceptibility of a collection of urine isolates to fosfomycin and compared multiple methods of susceptibility testing.

Impact of daptomycin resistance on Staphylococcus aureus virulence.

Daptomycin resistance (DAP(R)) in Staphylococcus aureus is associated with mutations in genes that are also implicated in staphylococcal pathogenesis. Using a laboratory-derived series of DAP exposed strains, we showed a relationship between increasing DAP MIC and reduced virulence in a Galleria mellonella infection model. Point mutations in walK and rpoC led to cumulative reductions in virulence and simultaneous increases in DAP MIC.

An enabling act.

Infection with human T-lymphotropic virus type 1 (HTLV-1) can be associated with hematologic malignancy, inflammatory syndromes, or infectious complications. Herein, we bring attention to HTLV-1 infection complications as we discuss a case of disseminated cryptococcosis in a patient with HTLV-1-associated T cell lymphoma.

Serine/threonine phosphatase Stp1 contributes to reduced susceptibility to vancomycin and virulence in Staphylococcus aureus.

The genetic mechanisms that contribute to reduced susceptibility to vancomycin in Staphylococcus aureus are complex and heterogeneous. In addition, debate is emerging as to the true effect of reduced susceptibility to vancomycin on staphylococcal virulence. To investigate this, comparative genomics was performed on a collection of vancomycin-exposed isogenic S.

Whole genome characterization of the mechanisms of daptomycin resistance in clinical and laboratory derived isolates of Staphylococcus aureus.

Background: Daptomycin remains one of our last-line anti-staphylococcal agents. This study aims to characterize the genetic evolution to daptomycin resistance in S. aureus.

Lack of bactericidal antagonism or synergism in vitro between oxacillin and vancomycin against methicillin-susceptible strains of Staphylococcus aureus.

With the current high prevalence of infection caused by methicillin-resistant Staphylococcus aureus (MRSA) strains but in light of the general belief that beta-lactam antibiotics are more effective than vancomycin against infections caused by methicillin-susceptible S. aureus (MSSA) isolates, clinicians may utilize antistaphylococcal penicillins in combination with vancomycin for the empirical treatment of S. aureus infections.

Analysis of clonality and antibiotic resistance among early clinical isolates of Enterococcus faecium in the United States.

Background: The Enterococcus faecium genogroup, referred to as clonal complex 17 (CC17), seems to possess multiple determinants that increase its ability to survive and cause disease in nosocomial environments.

Methods: Using 53 clinical and geographically diverse US E. faecium isolates dating from 1971 to 1994, we determined the multilocus sequence type; the presence of 16 putative virulence genes (hyl(Efm), esp(Efm), and fms genes); resistance to ampicillin (AMP) and vancomycin (VAN); and high-level resistance to gentamicin and streptomycin.

Development of reduced vancomycin susceptibility in methicillin-susceptible Staphylococcus aureus.

Background: Most cases of reduced vancomycin susceptibility in Staphylococcus aureus reported in the literature have been in methicillin-resistant strains. We report the development of reduced vancomycin susceptibility in a series of clonally related, methicillin-susceptible S. aureus (MSSA) clinical isolates.

Microbiology of drugs for treating multiply drug-resistant Gram-positive bacteria.

Several new antimicrobials demonstrate in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and other Gram-positive bacteria. Data from large surveys indicate that linezolid, daptomycin, and tigecycline are almost universally active against MRSA. Linezolid and tigecycline inhibit both Enterococcus faecium and Enterococcus faecalis at low concentrations; daptomycin is somewhat more potent against the latter.

Galleria mellonella as a model system to study Acinetobacter baumannii pathogenesis and therapeutics.

Nonmammalian model systems of infection such as Galleria mellonella (caterpillars of the greater wax moth) have significant logistical and ethical advantages over mammalian models. In this study, we utilize G. mellonella caterpillars to study host-pathogen interactions with the gram-negative organism Acinetobacter baumannii and determine the utility of this infection model to study antibacterial efficacy.

Reduced susceptibility to vancomycin influences pathogenicity in Staphylococcus aureus infection.

In the present study, we demonstrated the utility of the nonmammalian model system Galleria mellonella for studying the pathogenesis of Staphylococcus aureus infection. By use of clinical and laboratory strains that had been exposed to vancomycin, we showed that both agr functional status and vancomycin minimum inhibitory concentration are determinants associated with the virulence of S. aureus in G.

Prokaryote-eukaryote interactions identified by using Caenorhabditis elegans.

Prokaryote-eukaryote interactions are ubiquitous and have important medical and environmental significance. Despite this, a paucity of data exists on the mechanisms and pathogenic consequences of bacterial-fungal encounters within a living host. We used the nematode Caenorhabditis elegans as a substitute host to study the interactions between two ecologically related and clinically troublesome pathogens, the prokaryote, Acinetobacter baumannii, and the eukaryote, Candida albicans.

Evaluation of endocarditis caused by methicillin-susceptible Staphylococcus aureus developing nonsusceptibility to daptomycin.

We examined sequential methicillin-susceptible Staphylococcus aureus isolates from a patient with mitral valve endocarditis recovered during persistent bacteremia on standard therapy and relapse after treatment with daptomycin. An isolate obtained after 5 days of antimicrobial therapy, but before exposure to daptomycin, showed subtle physiological changes in response to daptomycin, with significant regrowth in the daptomycin killing assay compared to the treatment-naive strain. Once daptomycin was started, the population became more heterogeneous and tested as nonsusceptible.

Persistence of rRNA operon mutated copies and rapid re-emergence of linezolid resistance in Staphylococcus aureus.

Objectives: The G2576T mutation in domain V of 23S rRNA has been most often associated with the rare cases of linezolid resistance in Staphylococcus aureus. In a linezolid-susceptible S. aureus (A8761B) possessing a single mutated (G2576T) copy, originally derived from a resistant clinical isolate, we assessed the persistence of the mutation on further passage on antibiotic-free medium and the selection of resistance upon re-exposure of the susceptible strain to linezolid.

Daptomycin nonsusceptibility in Staphylococcus aureus with reduced vancomycin susceptibility is independent of alterations in MprF.

A previous study documented the presence of mutations in mprF that accompanied the loss of daptomycin susceptibility among Staphylococcus aureus isolates following exposure to the drug. An association between the development of glycopeptide-intermediate S. aureus and daptomycin nonsusceptibility has also been recently described.

Vancomycin-tolerant Streptococcus pneumoniae in Korea.

A nationwide surveillance study was undertaken to monitor antimicrobial resistance among clinical isolates of Streptococcus pneumoniae in Korea, with a special focus on vancomycin tolerance. For the 6-month period from March to August 2002, clinical isolates of S. pneumoniae were collected from 11 university hospitals and 1 reference laboratory.

Induction of daptomycin heterogeneous susceptibility in Staphylococcus aureus by exposure to vancomycin.

We studied vancomycin and daptomycin susceptibility in methicillin-resistant Staphylococcus aureus from patients exposed to vancomycin, glycopeptide-intermediate S. aureus, and S. aureus passaged in vancomycin-containing medium.